Simple Javascript Example sum = 0; for (i = 1; i < 10; i++) { - - PowerPoint PPT Presentation

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Simple Javascript Example sum = 0; for (i = 1; i < 10; i++) { - - PowerPoint PPT Presentation

Jul 17, 2023 335 likes •464 views

Simple Javascript Example sum = 0; for (i = 1; i < 10; i++) { sum += i*i; } CS 142 Lecture Notes: Javascript Slide 1 Arrays x = new Array(); x[3] = 49; y = ["a, 123, 65]; CS 142 Lecture Notes: Javascript Slide 2 Objects x =

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SLIDE 1

CS 142 Lecture Notes: Javascript Slide 1

Simple Javascript Example sum = 0; for (i = 1; i < 10; i++) { sum += i*i; }

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SLIDE 2

CS 142 Lecture Notes: Javascript Slide 2

Arrays x = new Array(); x[3] = 49; y = ["a“, 123, 65];

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CS 142 Lecture Notes: Javascript Slide 3

Objects x = new Object(); y = {name: "Alice", age: 23, state: "California"}; x.name = "Bob"; x["age"] = 21;

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CS 142 Lecture Notes: Javascript Slide 4

Factorial in Javascript function fac(x) { if (x <= 1) { return 1; } return x*fac(x-1); }

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CS 142 Lecture Notes: Javascript Slide 5

Method Example

  • = new Object();
  • .count = 0;
  • .increment = function(inc) {

if (inc == undefined) { inc = 1; } this.count += inc; return this.count; }

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SLIDE 6

CS 142 Lecture Notes: Javascript Slide 6

Functions Can Have Properties

function plus1(value) { if (plus1.invocations == undefined) { plus1.invocations = 0; } plus1.invocations++; return value+1; }

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SLIDE 7

CS 142 Lecture Notes: Javascript Slide 7

Constructor

function Rectangle(width, height) { this.width = width; this.height = height; } r = new Rectangle(26, 14);

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CS 142 Lecture Notes: Javascript Slide 8

Methods (wrong way)

function Rectangle(width, height) { this.width = width; this.height = height; this.area = function() { return this.width*this.height; } } r = new Rectangle(26, 14); a = r.area();

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SLIDE 9

CS 142 Lecture Notes: Javascript Slide 9

Prototypes

function Rectangle(width, height) { this.width = width; this.height = height; } Rectangle.prototype.area = function() { return this.width*this.height; } r = new Rectangle(26, 14); a = r.area();

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CS 142 Lecture Notes: Javascript Slide 10

Embedding Javascript

<body> ... <script type="text/javascript" src="myCode.js" /> <script type="text/javascript"> //<![CDATA[ alert("Page is loading"); //]]> </script> <p onclick="alert('Hello, world!');"> Click here.</p> ... </body>

External Javascript File Inline Code Event Handler

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CS 142 Lecture Notes: Cookies Slide 11